The pylons that support the Tacoma Narrows Bridge (called caissons) are cement monstrosities that plummet to into the intensely current swept passage between Tacoma and Gig Harbor. The are impressive structures above the water, and the submerged portion is simply a thrilling dive site.

First off, there are now two bridges - the old bridge to the north and the new bridge to the south. Each one has a supporting caisson on the east end and the west end, making four different possible caisson dives. They vary in depth from 110' deep on the side caissons nearest shore to 140+ on the inside of the caissons. Double check with a depth finder to verify the depth of your descent point.

The caissons on the Old Tacoma Narrows bridge are octagonal so it may seem as though you have swam around it and in actuality be far from it. They are covered with very large barnacles which provide shelter to a wide array of small sea-life including nudibranchs, cucumbers, anemones, and many varieties of sculpin, gunnels and pricklebacks. You may also find perch schooling and rockfish near the base. Drop in near the shore side on the West end and it is only about 110' deep to the bottom, providing a sense of security upon your descent.

The new bridge (south) provides the above listed visuals but with an additional dense population of colorful metridium which have taken hold of the newer concrete walls. They also have a large assortment of life on them and the two sets look very different from one another.

The top 20-25' of each caisson has many varieties of kelp, dense in some spots and a large portion of mussels. The bottom is covered in large barnacle encrusted rocks and debris that sank during the construction of the bridges. The most colorful and interesting portions of all of them are the top 50' or shallower so there is no need to spend an incredible amount of time at depth nor entering into deco on a potentially hazardous dive site.